Business Hours Calculator

A business hours calculator finds the number of working hours between two dates and times. It skips time outside the workday, lunch breaks, weekends, and holidays, so the result shows only time actually available for work.

This differs from a plain date calculator, which counts every hour in a range whether or not anyone is working.

How to calculate business hours

The calculation works day by day. For each day in the date range, the calculator does the following:

1. Check whether the day is excluded (a weekend or a holiday). Excluded days count as zero hours, unless the date is marked as an exceptional working day.
2. For the first and last day of the range, use the actual start or end time instead of the standard workday start or end.
3. Find the gross hours for the day: the work end time minus the work start time.
4. Subtract any part of the lunch break that falls inside those hours.
5. Add the day's net hours to the running total.

A holiday always excludes a day, even if that date is also marked as an exceptional working day. A date marked as an exceptional working day is included even if it falls on a normal weekend day.

Business hours formula

For one full workday:

Daily working hours = (work end time − work start time) − lunch break length

For example, a schedule from 8:00 AM to 5:00 PM is a 9-hour span. A 1-hour lunch break from 12:00 PM to 1:00 PM removes 1 hour. Net working time is 8 hours per day.

For a date range, the total is the sum of the net hours for every included day, with the first and last day adjusted to the actual start and end times.

Example calculation

Schedule: work hours 8:00 AM to 5:00 PM, lunch break 12:00 PM to 1:00 PM, weekends off (Saturday and Sunday), no holidays in range.

Range: Monday 8:00 AM to Friday 5:00 PM.

Total business hours: 8 × 5 = 40 hours. Total business days: 5.

Partial-day example

If the same range instead started at 10:00 AM on Monday, Monday would count only from 10:00 AM to 5:00 PM, minus the 1-hour lunch: 7 hours − 1 hour = 6 hours. The other four days stay at 8 hours each, so the total becomes 6 + 8 + 8 + 8 + 8 = 38 hours.

Business hours vs. calendar hours vs. business days

Calendar hours count every hour that passes, with no exclusions. From Monday 9:00 AM to Friday 5:00 PM, calendar hours total 104: four full 24-hour days (96 hours) plus 8 more hours from 9:00 AM to 5:00 PM on the last day.

Business hours count only working time, after removing non-work hours, lunch, weekends, and holidays. Using the schedule above, the same kind of Monday-to-Friday range yields 40 business hours, not 104.

Business days count whole working days, no matter how many hours were available on each one. Monday through Friday, with no holidays, is 5 business days, even if the first or last day is a partial day.

These three numbers answer different questions. A 40-hour task is roughly one work week (5 business days), not "less than 2 calendar days," and a 24-business-hour service commitment is not the same as a 24-calendar-hour one, since the business-hour version pauses overnight and on weekends.

Worked example: a response deadline

A support ticket opens on Thursday at 4:00 PM. The response commitment is 16 business hours, on the 8:00 AM–5:00 PM schedule above with a 12:00–1:00 PM lunch break and weekends off.

• Thursday: 4:00 PM to 5:00 PM = 1 hour. Running total: 1.
• Friday: a full day = 8 hours. Running total: 9.
• Saturday and Sunday: excluded.
• Monday: 7 more hours are needed. From 8:00 AM to 12:00 PM is 4 hours, then after the lunch break, 3 more hours from 1:00 PM reaches 4:00 PM.

The deadline is Monday at 4:00 PM.

Common uses

• Project planning: converting an hour estimate into a realistic delivery date.
• Freelance and consulting billing: counting hours actually available in a billing period.
• Payroll: computing hours worked for a pay period, including partial start or end days.
• Service level agreements (SLAs): measuring response or resolution deadlines that only run during business hours.

Frequently asked questions

What is a business hours calculator?

It is a tool that finds the total working time between two dates, after removing time outside the configured workday, lunch breaks, weekends, and holidays.

What is the difference between business days and business hours?

A business day is one whole working day, no matter how many hours were actually worked. Business hours are the exact hour count, including partial days. Five business days at 8 hours each equals 40 business hours only when every day is a full day; a range with a partial first or last day gives fewer business hours for the same number of business days.

How do I calculate business hours across time zones?

Convert every date and time to one reference time zone first, such as the time zone of the business or UTC. Calculating with mixed time zones produces wrong totals.

How are holidays that fall on a weekend handled?

If a holiday falls on a day that is already a weekend day, it does not need to be listed separately, since the weekend rule already excludes it. If the organization observes the holiday on a different day instead, list that observed date.

Why is the result lower than days × 8 hours?

A simple multiplication assumes every day is a full 8-hour day with no exclusions. Real ranges usually include a partial first or last day, weekends, and sometimes holidays, all of which reduce the total below a plain multiplication.

Can exceptional working days override a weekend?

Yes. A specific date can be marked as an exceptional working day so it counts even though it falls on a normal weekend. A holiday exclusion still takes priority: a date marked as both a holiday and an exceptional working day is excluded.